How to read DIS plug

[Graham Thackrah]

Hi Matt,

Bugger, you meant the other little black box under there, that'll teach
me to check mail first thing in the morning!

Simple DIS checking is to let the engine warm up then check timing at
idle, then whack on everything electrical you can think of and see if
the timing has changed (advanced), if it hasn't the DIS is probably
faulty. Sorry for the confusion.

Graham.